This invention relates generally to gas generation and, more particularly, to devices and methods for inflating an inflatable device such as an inflatable vehicle occupant restraint of a respective inflatable restraint system.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an xe2x80x9cairbag cushion,xe2x80x9d that is inflated or expanded with gas such as when the vehicle encounters sudden deceleration, such as in the event of a collision. In such systems, the airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins to be inflated, in a matter of no more than a few milliseconds, with gas produced or supplied by a device commonly referred to as an xe2x80x9cinflator.xe2x80x9d
Many types of inflator devices have been disclosed in the art for the inflating of one or more inflatable restraint system airbag cushions. Prior art inflator devices include compressed stored gas inflators, pyrotechnic inflators and hybrid inflators. Unfortunately, each of these types of inflator devices has been subject to certain disadvantages such as one or more of having a greater than desired weight, requiring more than desired space or volume, producing undesired or nonpreferred combustion products in greater than desired amounts, and producing or emitting gases at a greater than desired temperature, for example. Further, in those inflator devices that rely upon the reaction of a gas generant material or fuel to produce or provide inflation gas, the cost of producing or supplying such gas generant material or fuel and associated inflator device may be greater than would otherwise be desired.
Thus, there remains a need and a demand for a gas generating device, particularly for application in an apparatus for inflating an inflatable device, and methods of inflation that more freely permit the use of lower cost reactant materials.
There has been and continues to be significant interest in gas generant compositions incorporation and use of ammonium nitrate. In particular, ammonium nitrate is a relatively low cost, readily available and generally high gas yield component material for inclusion in such compositions.
Unfortunately, the general incorporation and use of ammonium nitrate in pyrotechnic gas generant formulations have generally been subject to certain difficulties. For example, ammonium nitrate-containing pyrotechnic gas generant formulations have commonly been subject to phase or other changes in crystalline structure such as may be associated with volumetric expansion such as may occur during temperature cycling over the normally expected or anticipated range of storage conditions, e.g., temperatures of about xe2x88x9240xc2x0 C. to about 110xc2x0 C. Such changes of form or structure may result in physical degradation of such gas generant formulation forms such as when such a gas generant formulation has been shaped or formed into tablets, wafers or other selected shape or form. Further, such changes, even when relatively minute, can strongly influence the physical properties of a corresponding gas generant material and, in turn, strongly affect the burn rate of the generant material. Unless checked, such changes in ammonium nitrate structure may result in such performance variations in the gas generant materials incorporating such ammonium nitrate as to render such gas generant materials unacceptable for typical inflatable restraint system applications.
In view of the above, there is a need and a demand for a gas generating device, an apparatus for inflating an inflatable device and a method for inflation that enhance the likelihood of greater or more widespread use of reactant materials such as ammonium nitrate.
A general object of the invention is to provide an improved gas generation or inflation device and method for inflating an inflatable safety device.
A more specific objective of the invention is to overcome one or more of the problems described above.
The general object of the invention can be attained, at least in part, through an apparatus for inflating an inflatable safety restraint cushion and which apparatus includes a first container containing a supply of elemental carbon. The apparatus also includes a first chamber having contents including a supply of oxidant source material, wherein the oxidant source material comprises a supply of nitrous oxide. The apparatus further includes a container opener, an initiator device and a diffuser assembly. The chamber opener is effective upon actuation to open the first container and place at least a portion of the supply of elemental carbon in reaction communication with at least a portion the first chamber contents. The initiator device is effective to initiate reaction between at least a portion of the supply of elemental carbon and at least a portion the first chamber contents to form a gaseous inflation medium. The diffuser assembly includes at least one outlet opening for directing gaseous inflation medium discharged from the first chamber to the inflatable device.
The prior art has generally failed to provide an inflator device and inflation method that permits and facilitates the use of low cost fuel materials, such as elemental carbon, in gas generation or production and, in particular, for gas generation or production for use in the inflation of inflatable restraint system airbag cushions. The prior art also has generally failed to provide an inflator device and inflation method that may desirably facilitate or otherwise more easily permit the advantageous use of compounds such as ammonium nitrate without incurring undesired complications such as described above relating to form and structure on the ammonium nitrate and the resulting performance characteristics thereof.
The invention further comprehends an apparatus for inflating an inflatable safety restraint cushion. In accordance with one preferred embodiment of the invention, such an apparatus includes a first container having contents including a supply of elemental carbon, a supply of ammonium nitrate and a supply of boron potassium nitrate. The apparatus also includes a first chamber having contents including a supply of nitrous oxide and a supply of carbon dioxide; wherein the first chamber contents are contained therewithin in a static state in an at least partially liquified form. The apparatus further includes a container opener effective upon actuation to open the first container and place at least a portion of the supply of elemental carbon in reaction communication with at least a portion the first chamber contents. Also, the apparatus includes an initiator device effective to initiate reaction between at least a portion of the supply of elemental carbon and at least a portion the first chamber contents to form a gaseous inflation medium and a diffuser assembly including at least one outlet opening for directing gaseous inflation medium discharged from the first chamber to the inflatable device.
The invention still further comprehends a method of or for inflating an inflatable safety restraint cushion. In accordance with one such preferred embodiment of the invention, such method involves reacting elemental carbon with an oxidant within an inflator device to form a gaseous inflation medium and then directing at least a portion of the gaseous inflation medium flowing through at least one outlet opening out of the inflator device.
As used herein, the references to xe2x80x9celemental carbonxe2x80x9d are to be understood to refer to generally refer to carbon in an uncombined form. It will be appreciated that elemental carbon in accordance with the invention may contain or include small or minor amounts of impurities, such as are known or commonly associated with carbon.
Other objects and advantages will be apparent to those skilled in the art from the following detailed description taken in conjunction with the appended claims and drawings.